This invention relates to wireless telephony and has particular relation to configuring a wireless terminal.
A wireless terminal emulates a standard wireline wall jack. A standard telephone will plug unto either of them, using a standard RJ-11 interface. A standard wireline wall jack, however, is attached to a 2-wire or 4-wire cable and sends and receives analog signals. A wireless terminal (in contrast) digitizes, modulates, and transmits the signals over an antenna; or it receives them from the antenna, and demodulates them before converting them to analog.
However, a standard telephone is not the only thing which will plug into an RJ-11 interface, whether the interface is to a wireline wall jack or to a wireless terminal. Fax machines, computers (and different computes use different modems, of the Bell type or the V-series type), and numerous other devices are all configured to use the standard RJ-11 interface. Each device compresses the data flowing from it (and decompresses the data flowing to it) in the way best suited to it, without regard to the data compression schemes used by other devices.
This wide variety of data compression schemes presents no problem to a wireline wall jack. There is an analog local loop (typically of copper wire) between the jack and the telephone company""s first piece of equipment, and this local loop has a fairly broad bandwidth. Any reasonable data compression scheme can be accommodated. Moreover, to the extent that the analog wireline local loop does impose limits, these limits have been carefully considered in crafting the data compression scheme for the device at hand. There is a large installed base of devices, each using one of a fairly small number of compression schemes.
With a wireless terminal, however, the local loop to the first piece of telephone company equipment (the base station) has a much narrower bandwidth, and it is digital. The digitization process must be carefully matched to the data compression scheme being used. Therefore, a wireless terminal which has been designed to interface with a computer using, for example, a Bell modem will not work properly with a different computer using the more modem V-series modem, and vice versa. Bell modems, among other things, operate only at and below 1200 bits per second. Above that speed, all modems use V-series. If a user has two computers, one with a Bell modem and one with a V-series modem, then he needs two wireless terminals. This is true even though he never uses both computer/modem/wireless-terminal combinations at the same time. He needs yet a third wireless terminal to run his fax machine, a fourth terminal for some other device, and so on.
This requirement for multiple wireless terminals is wasteful. It has long been considered a necessary price to pay, however. The alternative is to abandon the large installed base of devices which were designed for wireline use, and create a new base of devices designed for wireless use. Not only is it wasteful to abandon perfectly good equipment, but it would create the requirement for multiple devicesxe2x80x94one for wireless, one for wireline. This is even more expensive than the current system of multiple wireless terminals.
Applicants have noticed that the physical characteristics of the signals being exchanged by the device and the wireless terminal are comparable regardless of what the device is. The wireless terminal""s hardware, if capable of producing the correct voltages, frequencies, and power levels for one type of device, is generally capable of producing the correct voltages, frequencies, and power levels for the other types of devices as well. This capability results from the requirement that all devices be compatible with the wireline network. The significant difference between devices is not the physical characteristics of the signals, but the device algorithm used to produce them.
Applicants therefore provide a switch in the wireless terminal. Different settings of the switch cause a processor in the wireless terminal to use different device algorithms. The switch itself is set by applying a code signal to the wireless terminal through its RJ-11 interface. The code is a sequence of Dual Tone Multiple Frequency (DTMF) tones, which may conveniently be provided by the device itself, or by an ordinary telephone or any other device.
The present invention is not limited to computer modems, but applies to any device. Using the present invention, the user may use DTMF tones to control the behavior of the wireless terminal, no matter what device is using the terminal.